ABD region x-ray examinations account for about 25% of all diagnostic x-ray exams. What percent of all repeats are from films of this region?

ABD region x-ray examinations account for about 25% of all diagnostic x-ray exams. What percent of all repeats are from films of this region?

• A. 20%
• B. 40%
• C. 60%
• D. 80%

Answer: (B)

When figuring repeats, use proportional reasoning with different repeat rates for each region. ABD exams are 25% of all exams, but repeats for ABD images occur at twice the rate of repeats for other regions. So imagine 100 initial exams: 25 ABD and 75 non-ABD. If ABD repeats are twice as likely, ABD repeats = 25 × 2 = 50. Non-ABD repeats = 75 × 1 = 75. Total repeats = 50 + 75 = 125. The portion from ABD repeats is 50 out of 125, which is 50/125 = 0.40, or 40%. Thus, 40% of all repeats come from ABD region.

When figuring repeats, use proportional reasoning with different repeat rates for each region. ABD exams are 25% of all exams, but repeats for ABD images occur at twice the rate of repeats for other regions.

So imagine 100 initial exams: 25 ABD and 75 non-ABD. If ABD repeats are twice as likely, ABD repeats = 25 × 2 = 50. Non-ABD repeats = 75 × 1 = 75. Total repeats = 50 + 75 = 125. The portion from ABD repeats is 50 out of 125, which is 50/125 = 0.40, or 40%.

Thus, 40% of all repeats come from ABD region.